PARIS/MADRID (Reuters) - French state-controlled nuclear group Areva AREVA.PA and Spanish wind turbine maker Gamesa GAM.MC have agreed a preliminary deal to create one of the biggest players in offshore wind energy.

The companies will have 50 percent each in the new joint venture, they said in a combined statement on Monday. Reuters had reported on Friday that they were in advanced talks.

“Offshore wind energy is one of the renewable energies with the most growth potential in the coming years, especially in coastal countries in Northern Europe ... and in Asia,” the statement said.

They added that the alliance would lead to “significant synergies”, without giving any figures, and that they expect a final agreement to be signed in the summer.

The venture will enable the companies to share the risk associated with the hefty cost of research and development, as well the work to adapt factories for the production of wind turbines.

It follows a similar move by the world’s biggest maker of onshore wind turbines, Denmark’s Vestas Wind Systems (VWS.CO), which unveiled a joint venture with Japan’s Mitsubishi Heavy Industries (7011.T) for offshore wind turbines in September.

“By choosing to create a European offshore wind champion with Gamesa, Areva is playing a key role in the consolidation, already underway, of the offshore wind sector and confirms its long-term commitment to renewable energies,” Areva Chief Executive Luc Oursel said.

Areva, which builds nuclear reactors and mines uranium, has been struggling to diversify into offshore wind energy and does not make onshore turbines. Its loss-making renewables arm contributed only 6 percent of 2012 revenue.

Gamesa, 19.7 percent owned by Iberdrola (IBE.MC), has stepped up efforts to expand abroad since the Spanish government passed a tough energy reform last July, including a reduction in public subsidies to producers of clean energy.